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Re: Subject: Bird hibernation/torpor



At 04:07 PM 3/21/97 -0500, John Bois wrote:
>And his temperature drops and his urine becomes concentrated.  Is it
>_adaptationist_ of me to suggest he does this in order to keep the nest
>site stealthy?  Are there alternate hypotheses for this behavior? 

There is nothing particularly "stealthy" about an Emu's nest, but certainly
continuous brooding reduces the likelihood of predation.  There may be
other explanations, though. A male Emu repulses the female once he starts
to brood, and prevents her from laying again; female Emus will visit the
territory of other males.  It may be (and this is just my guess) that the
male may be trying to prevent laying by the female, or another female, of
eggs fathered by another male.  We are now learning that this sort of
"sperm competition" is much more widespread in birds than we had thought,
though I do not know if it is known in ratites.  To give an example,
Aquatic Warblers have the most prolonged copulation in birds (over 20
minutes!), apparently as a way of keeping other males away from the female
when she is receptive.
--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court                 
Mississauga, Ontario, Canada L5L 3W2          Internet: ornstn@inforamp.net